1. Field of the Invention
The present invention relates to a method for producing an integrated optical device.
2. Description of the Related Art
Patent Reference 1 (Japanese Unexamined Patent Application Publication No. 2010-283104) describes an integrated optical device having a butt-joint structure. This integrated optical device has a ridge waveguide structure. Patent Reference 1 describes the following method for producing an integrated optical device. First, an n-type InP lower cladding layer, an active layer, a grating layer, and a p-type InP cover layer that are to constitute a semiconductor laser are grown on an n-type InP substrate. Second, portions of the n-type InP lower cladding layer, the active layer, and the p-type InP cover layer are removed by wet etching. After that, on the region of the n-type InP substrate from which the portions have been removed, an n-type InP lower cladding layer, an active layer, and a p-type InP cover layer that are to constitute an electric absorption optical modulator are grown. As a result, the active layer of the electric absorption optical modulator is coupled to the active layer of the semiconductor laser by a butt-joint method. The p-type InP cover layer is then removed. A diffraction grating is subsequently formed in the grating layer of the semiconductor laser. A p-type InP upper cladding layer is grown over the semiconductor laser and the electric absorption optical modulator. A ridge structure extending in a predetermined waveguiding direction is then formed.